Recent wireless communication appliances including portable telephones and wireless LAN devices are being produced in progressively smaller and thinner packages. Such wireless communication appliances are assembled from numerous components including various SAW filters suitable for performing filtering and resonating functions. The devices mentioned above are required to incorporate an increasing number of functions, and therefore SAW filters are increasingly employed to accomplish this end. In order to manufacture wireless communication appliances and modules in a compact size, packaged SAW filters must be made smaller.
Conventional SAW filters are manufactured according to the following process: a circuit for a SAW filter, typically formed on a piezoelectric substrate, is mounted on an LTCC (Low Temperature Co-fired Ceramic) substrate via a flip-chip or a wire bonding connection process. The exterior of the piezoelectric substrate is then covered with a polymer layer, with the exception of the bottom surface. The outer surface of the polymer is coated with a metal layer to provide shielding, thereby protecting the active region, the input/output bonding pads and the terminals (typically solder bumps that are positioned on the bottom surface of the substrate of the SAW filter), from the external environment. The LTCC substrate of the SAW filter is then mounted on a motherboard and the LTCC substrate having the SAW filter mounted thereon is encapsulated by an encapsulant, along with other electronic devices.
However, the above-described manufacturing process is prolonged and expensive, as the piezoelectric substrate is essentially mounted twice: first on the LTCC substrate, and then the LTCC substrate is mounted on the motherboard. Also, the dual mounting increases the size of the SAW filter, because the size of the LTCC substrate on which the SAW filter is mounted is larger than that of the SAW filter piezoelectric substrate.
Therefore, it would be desirable to provide a SAW device package and method for packaging a SAW device having a reduced cost, simplified manufacturing process and reduced size.